Generally, magnetic hard disc drives include transducer heads that read and write data encoded in tangible magnetic storage media. Magnetic flux detected from the surface of the magnetic medium causes rotation of a magnetization vector of a sensing layer or layers within a magnetoresistive (MR) sensor within the transducer head, which in turn causes a change in electrical resistivity of the MR sensor. The change in resistivity of the MR sensor can be detected by passing an electrical current through the MR sensor and measuring the resulting change in voltage across the MR sensor. Related circuitry can convert the measured voltage change information into an appropriate format and manipulate that information to recover the data encoded on the disc.
As improvements in magnetic recording density capabilities are pursued, the dimensions of transducer heads continue to shrink. Typically, transducer heads are formed as a thin film multilayer structure having an MR sensor, among other structures. In some approaches, such as magnetoresistive sensors that utilize tunnel magnetoresistance (TMR) or giant magnetoresistance (GMR) effects, the thin film multilayer structure includes an antiferromagnet (AFM) and a synthetic anti-ferromagnet (SAF) to enhance MR sensor stability. However, the presence of an AFM/SAF structure can nevertheless limit future downscaling of the MR sensor. In addition, electrical current passed through sensing layers of some MR sensors can generate thermal noise that degrades a signal-to-noise (SNR) ratio of the sensor.